Devices for maintaining water levels in water containers for stock yard animals are known, however these devices generally operate using valves and ballcocks. These devices, which usually operate under mains pressure or tank pressure, suffer from a disadvantage that the valves often become blocked or leak or that the ballcock floatation mechanism breaks down and fails to function effectively.
Other devices are known which rely on a partial vacuum created in an upturned water container to control the supply of water to the water receptacle. These vacuum operated devices suffer from the disadvantage that they must be upturned while full of water. Accordingly the size of such containers is limited.
Australian patent number 147,682 is an attempt to overcome the fundamental requirement of inverting the container in systems where the water reservoir is maintained by vacuum. The design of the watering device allows the vessel to be filled without inversion, however, since the top of the outer container is not an airtight seal, water in the small annular gap between the inner and outer vessels is free to dribble out of the small outlet orifice regardless of its level in the lower dish. This will, as stated, block the lower end of the tube preventing air inflow by this path but as this water drains through the orifice it will eventually allow an airpath under the bottom of the inner container.
Accordingly it appears that all water would slowly drain out of the inner vessel and the lower dish continuously overflow unless the outlet orifice is raised in height from that suggested in the patent. The patent also specifies that the air inlet tube must extend substantially vertically from the open topped receptacle into the vessel containing the liquid supply. Accordingly the device suffers from the disadvantage that the vessel containing the liquid supply must be located substantially vertically above the open topped receptacle.
In all known devices of the type in which the water reservoir is maintained by partial vacuum the vessel containing the water supply is necessarily located within, or in close proximity to, the water receptacle. Generally the vessel containing the water supply and the water receptacle are manufactured as a single unit. As such both the vessel and the receptacle are located inside the animal or bird enclosure and it is necessary to enter the enclosure when the water vessel is to be refilled. It would be convenient to provide a device which could be located outside the enclosure or at least in a position remote from the water receptacle.
It is an object of the present invention to overcome or at least alleviate one or more of the above mentioned disadvantages of the prior art.